**Exhibit 10.9**

[BIOTRANSPLANT LOGO]

Building75, 3rd AvenueCharlestown Navy YardCharlestown, MA 02129Tel: 617/241-5200Fax: 617/241-8780

July 30, 1991

Dr. Mary White-Scharf19 Johnson RoadWinchester, MA 01890

Dear Mary:

This letter will confirm our offer to youto join BioTransplant, Inc. on the following terms:
| Title:        | Director  of the Monoclonal Antibody Department reporting to the Vice President of  Research and Development                                                                                                                                                                             |
|---------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
|          |                                                                                                                                                                                                                                                                                     |
| Terms:        | This  offer is contingent on your starting on or before September 9, 1991.                                                                                                                                                                                                               |
|          |                                                                                                                                                                                                                                                                                     |
| Compensation: | $70,000  per year                                                                                                                                                                                                                                                                        |
|          |                                                                                                                                                                                                                                                                                     |
| Equity:       | To  be determined by the Board of Directors                                                                                                                                                                                                                                              |
|          |                                                                                                                                                                                                                                                                                     |
| Agreements:   | Your  employment is subject to your signing a Confidentiality, Invention Agreement  and a Non-Compete Agreement with BioTransplant and review of any agreement  you may have with others to insure that your employment with BioTransplant is  not in conflict with any such agreements. |

If these terms are acceptable, pleasesign and return one copy of this agreement.

We look forward to your joining thecompany and sharing in our new challenge.

Best regards,

/s/ Bernice Schacter, Ph.D.Bernice Schacter, Ph.D.Vice President Research & Development

AGREED TO:
| By:    |  /s/ Mary White-Scharf, Ph.D. |   | Date:  | 8/7/91 |
|--------|------------------------------------|--------|--------|--------|
|   |                                    |   |   |        |
|   | Mary  White-Scharf, Ph.D.          |   |   |   |

[BIOTRANSPLANT LOGO]

Building75, 3rd AvenueCharlestown Navy YardCharlestown, MA 02129Tel: 617/241-5200Fax: 617/241-8780

March31, 1996

Dr. Mary White-Scharf14 Johnson RoadWinchester, MA 10890

Dear Mary:

             Referenceis made to the Letter Agreement dated July 30, 1991, by and betweenBioTransplant Incorporated and you (the “Letter Agreement”).  The Letter Agreement is hereby amended toadd the following additional term:
|   | Severance: | In  the event your employment is terminated without cause, you will receive up to  6 months base salary, payable in 12 equal installments which will be  discontinued upon your securing other employment. |
|--------|------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

             Pleasesign below to acknowledge your agreement with the foregoing.
|   | Very  truly yours,                     |
|--------|----------------------------------------|
|   |                                   |
|   | /s/  Elliot Lebowitz                   |
|   |                                        |
|   | Elliot  Lebowitz, Ph.D.                |
|   | President  and Chief Executive Officer |

AGREED:
| By:    | /s/  Mary White-Scharf |
|--------|------------------------|
|   |                        |
|   | Mary  White-Scharf     |

Date: April 15, 1996